In facilities such as distribution centers or large warehouses, acres of articles are handled on a daily basis. A large warehouse, for example, has large-scaled rack frames arranged in a plurality of rows. Such a rack frame is elongated, stretching over 10 meters in length, and has a plurality of rows of rack shelves.
Generally, in such facilities, palletized articles are loaded into and/or unloaded from a rack frame having a plurality of rows of rack shelves by a self-propelled carrier such as a forklift (self-propelled material handling equipment). The depth of each rack shelf into and from which a forklift can load and unload articles is limited by a length of forks of the forklift, being no more than the depth of one pallet. As a result, articles are inevitably loaded into and unloaded from a rack frame from a front side perpendicular to its longitudinal direction.
This renders rack frames unable to be arranged without space between the frames and requires passages between the frames through which the forklift moves. Hence, large warehouses according to the art need to have passages between rack frames and some facilities having a limited area easily come to face limit of a handling quantity of articles. In order to solve such a problem described above, the patent document 1 specified below discloses an article storage facility.
Specifically, the patent document 1 discloses an article storage facility having a plurality of short conveyors connected in a rack frame. The storage facility disclosed in the patent document 1 loads an article by a forklift from one side in a longitudinal direction of the rack frame and transfers the article, which has been placed on each conveyor driven by an electric motor, over the conveyors, thereby storing the article in the rack frame. The stored article is optionally unloaded from the other side in the longitudinal direction of the rack frame by a forklift. In other words, the rack frame can arrange a plurality of articles serially in its longitudinal direction, thereby dispensing with a passage between shelves, which was required before. That produces greater occupancy of articles per area in such facilities. Shortly, even facilities having limited areas can handle acres of articles.